In conventional electronic systems provided with at least one buzzer, in particular provided with a piezoelectric element, there is provided a coil linked to the buzzer, and both are connected to a control circuit. The control circuit may include a transistor arranged in series with the coil and the buzzer between two terminals of a supply voltage source. When the electronic system is put into operation to generate a sound, such as an alarm, pulses are applied to the gate or base of the transistor to excite the assembly formed by the coil and the buzzer.
Generally, it is sought to adjust the frequency of the control circuit as a function of the resonance frequency of the assembly formed by the coil and the buzzer. To achieve this, a first phase must be provided for measurement of the resonance frequency. Then, in a feedback loop, the response of the mechanical sound generation assembly can be sampled, to adjust the frequency of the control pulses. This frequency must be adjusted close to the resonance frequency of the mechanical sound generation assembly to generate a sound having sufficient sound level while limiting the electrical energy required. However, it is noted that it is difficult for the control circuit to work permanently at this adjusted frequency, since the mechanical assembly often experiences a natural change in its physical parameters over time. Replacement of the resonant system in an after-sales operation can also impair the efficiency of the original device. This constitutes a drawback of such a conventional electronic system.